Non-cycloplegic spherical equivalent refraction in adults:comparison of the double-pass system, retinoscopy, subjective refraction and a table-mounted autorefractor

Abstract

AIM:To evaluate the accuracy of spherical equivalent (SE) estimates of a double-pass system and to compare it with retinoscopy, subjective refraction and a table-mounted autorefractor.METHODS: Non-cycloplegic refraction was performed on 125 eyes of 65 healthy adults (age 23.5±3.0 years) from October 2010 to January 2011 using retinoscopy, subjective refraction, autorefraction (Auto kerato-refractometerTOPCON KR-8100, Japan) and a double-pass system (Optical Quality Analysis System, OQAS, Visiometrics S.L., Spain). Nine consecutive measurements with the double-pass system were performed on a subgroup of 22 eyes to assess repeatability. To evaluate the trueness of the OQAS instrument, the SE laboratory bias between the double-pass system and the other techniques was calculated.RESULTS:The SE mean coefficient of repeatability obtained was 0.22D. Significant correlations could be established between the OQAS and the SE obtained with retinoscopy (r=0.956, Pr=0.955, Pr=0.957, PPCONCLUSION: The double-pass system provides accurate and reliable estimates of the SE that can be used for clinical studies. This technique can determine the correct focus position to assess the ocular optical quality. However, it has a relatively small measuring range in comparison with autorefractors (-8.00 to +5.00D), and requires prior information on the refractive state of the patient.

Keywords

• double-pass system
• optical quality
• retinoscopy
• autorefraction
• subjective refraction
• accuracy
• repeatability
• trueness